Composition of air and pollutants

Imagine air like a delicious fruit smoothie. It's not just one ingredient; it's a mix of many different things! The composition of air (what air is made of) is mostly gases, with a tiny bit of other stuff.

Here's the recipe for our 'air smoothie':

• Nitrogen (N₂): This is the biggest part, like the main liquid in your smoothie (maybe water or milk). It makes up about 78% of the air. It's pretty chill and doesn't react much.
• Oxygen (O₂): This is the second biggest part, like the main fruit in your smoothie (strawberries, perhaps!). It makes up about 21% of the air. This is the super important gas that we (and most living things) need to breathe to live.
• Argon (Ar): This is a smaller ingredient, like a little bit of banana. It's about 0.9%.
• Carbon Dioxide (CO₂): This is a tiny but very important ingredient, like a pinch of sugar or honey. It's about 0.04%. Plants use it to make their food!
• Other Gases: Even tinier amounts of other gases, like neon, helium, and methane, are also present.
• Water Vapour: This is like the ice in your smoothie – sometimes there's a lot, sometimes there's a little, depending on the weather (humidity).

Now, imagine someone accidentally drops something yucky into your smoothie – that's a pollutant! Air pollutants are unwanted substances (things that shouldn't be there) in the air that can harm living things and the environment. They're like bad ingredients that spoil the whole mix.

Let's think about a busy city street, like when cars are stuck in traffic. When you're walking by, sometimes you can smell a strong, unpleasant odor, or even see a hazy cloud. That's a real-world example of air pollution in action!

1. Cars are running: Each car's engine burns fuel (like petrol or diesel) to make it move.
2. Burning fuel isn't perfect: When fuel burns, it doesn't just produce harmless gases. It also releases things like carbon monoxide (a poisonous gas), nitrogen oxides (gases that cause smog and acid rain), and tiny bits of soot (carbon particles).
3. These are pollutants: These extra gases and particles are the 'yucky stuff' that gets added to our 'air smoothie'. They weren't part of the original, healthy air recipe.
4. Impact: Breathing in these pollutants can make people cough, make their eyes sting, and over time, can cause serious breathing problems like asthma. They also contribute to a hazy sky (smog) and can damage buildings and plants.

Let's break down how pollutants get into our air and what they do:

1. Source: Something releases a harmful substance into the air. This could be a factory chimney or a car exhaust pipe.
2. Emission: The harmful substance, like smoke or gas, leaves its source and enters the atmosphere (the air around Earth).
3. Dispersion: Wind and air currents spread these pollutants around, mixing them with the normal air. Think of it like dropping ink into water; it spreads out.
4. Reaction (sometimes): Some pollutants can react with other gases in the air or with sunlight to form new, even more harmful substances. This is how smog often forms.
5. Impact: These pollutants then affect living things (like us, animals, and plants) and non-living things (like buildings and water bodies).
6. Removal: Eventually, some pollutants are removed from the air by rain (acid rain is an example) or by settling down onto surfaces, but this can take time.